Plunge base routers have long been used to make grooves and cuts of various types. Such routers include a housing having a motor which rotates a router bit for making grooves and cuts in a work. The housing is vertically movable relative a base on two guide posts that are connected to the base. It is known that a plunge base router can be used in an upright (or normal position) and an inverted position for use under a router table. In the upright position, the router can plunge on the posts and is used to make cutouts, for grooving and edge-forming of wood or other solid-surface materials. When the router is mounted under the table, it is used like a shaper mainly for cutting repetitive shapes and for heavy decorative edge-cuts. When used in the upright position, the term cutting depth is used to describe the amount that the bit is exposed through the base. When used in the inverted position, the term cutting height describes the amount that the bit is exposed above the router table.
Typically, the housing of the plunge base router is slidable on the guide posts to permit plunging of the router and positioning of the housing relative to the base. The housing contains a compression spring adjacent to at least one of the guide posts for biasing the housing away from the base. The compression spring may be on the outside or inside of the post. Most plunge base routers provide a depth adjustment mechanism to accurately position the bit at the correct cutting depth or height. Some routers provide a coarse adjustment mechanism to generally find the depth or height and a fine adjustment mechanism to accurately locate the depth or height. The coarse and fine adjustment mechanisms are both used to arrange the router for the desired cutting depth or height.